The objectives of this project are to study in the experimental animal various aspects of thrombotic and nonthrombotic coronary occlusion, with particular emphasis on platelet behavior; their effects upon hemodynamic and electrical properties of the myocardium and the results of therapeutic intervention. Thrombotic, nonthrombotic and microcirculatory coronary occlusion will be induced and their characteristics and effects upon myocardium will be studied. Therapeutic interventions, using antiplatelet aggregating agents, will be evaluated to obtain objective documentation (by means of parameters of cardiac function) of their postulated therapeutic value. A further objective is in vivo diagnosis of coronary artery thrombosis using a scintillation camera and radioisotopically labelled agents participating in the formation or lysis of thrombus (fibrinogen, platelets, fibrinolytic agents). The studies will be expanded into developing technics related to in vivo detection of myocardial ischemia. Further, an attempt will be made to devise methods capable of quantitating myocardial ischemia to be used diagnostically and prognostically in connection with various forms of therapeutic interventions aimed at modifying the outcome of myocardial infarction. BIBLIOGRAPHIC REFERENCES: Chowdhury, P. and Moschos, C.B.: Effects of experimental coronary thrombosis upon regional and systemic plasma chromatographic patterns. Thrombosis et Diathesis Haemorrhagica (in press), 1975. Moschos, C.B., Regan, T.J., Lyons, M.M. and Oldewurtel, H.A.: The role of platelets in catecholamines induced myocardial injury. Fed. Proceed. 34: 873. 1975.